cpuset.c 71.9 KB
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/*
 *  kernel/cpuset.c
 *
 *  Processor and Memory placement constraints for sets of tasks.
 *
 *  Copyright (C) 2003 BULL SA.
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 *  Copyright (C) 2004-2007 Silicon Graphics, Inc.
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 *  Copyright (C) 2006 Google, Inc
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 *
 *  Portions derived from Patrick Mochel's sysfs code.
 *  sysfs is Copyright (c) 2001-3 Patrick Mochel
 *
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 *  2003-10-10 Written by Simon Derr.
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 *  2003-10-22 Updates by Stephen Hemminger.
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 *  2004 May-July Rework by Paul Jackson.
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 *  2006 Rework by Paul Menage to use generic cgroups
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 *  2008 Rework of the scheduler domains and CPU hotplug handling
 *       by Max Krasnyansky
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 *
 *  This file is subject to the terms and conditions of the GNU General Public
 *  License.  See the file COPYING in the main directory of the Linux
 *  distribution for more details.
 */

#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/cpuset.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/list.h>
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#include <linux/mempolicy.h>
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#include <linux/mm.h>
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#include <linux/memory.h>
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#include <linux/module.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/pagemap.h>
#include <linux/proc_fs.h>
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#include <linux/rcupdate.h>
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#include <linux/sched.h>
#include <linux/seq_file.h>
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#include <linux/security.h>
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#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/time.h>
#include <linux/backing-dev.h>
#include <linux/sort.h>

#include <asm/uaccess.h>
#include <asm/atomic.h>
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#include <linux/mutex.h>
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#include <linux/workqueue.h>
#include <linux/cgroup.h>
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/*
 * Tracks how many cpusets are currently defined in system.
 * When there is only one cpuset (the root cpuset) we can
 * short circuit some hooks.
 */
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int number_of_cpusets __read_mostly;
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/* Forward declare cgroup structures */
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struct cgroup_subsys cpuset_subsys;
struct cpuset;

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/* See "Frequency meter" comments, below. */

struct fmeter {
	int cnt;		/* unprocessed events count */
	int val;		/* most recent output value */
	time_t time;		/* clock (secs) when val computed */
	spinlock_t lock;	/* guards read or write of above */
};

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struct cpuset {
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	struct cgroup_subsys_state css;

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	unsigned long flags;		/* "unsigned long" so bitops work */
	cpumask_t cpus_allowed;		/* CPUs allowed to tasks in cpuset */
	nodemask_t mems_allowed;	/* Memory Nodes allowed to tasks */

	struct cpuset *parent;		/* my parent */

	/*
	 * Copy of global cpuset_mems_generation as of the most
	 * recent time this cpuset changed its mems_allowed.
	 */
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	int mems_generation;

	struct fmeter fmeter;		/* memory_pressure filter */
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	/* partition number for rebuild_sched_domains() */
	int pn;
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	/* for custom sched domain */
	int relax_domain_level;

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	/* used for walking a cpuset heirarchy */
	struct list_head stack_list;
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};

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/* Retrieve the cpuset for a cgroup */
static inline struct cpuset *cgroup_cs(struct cgroup *cont)
{
	return container_of(cgroup_subsys_state(cont, cpuset_subsys_id),
			    struct cpuset, css);
}

/* Retrieve the cpuset for a task */
static inline struct cpuset *task_cs(struct task_struct *task)
{
	return container_of(task_subsys_state(task, cpuset_subsys_id),
			    struct cpuset, css);
}
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struct cpuset_hotplug_scanner {
	struct cgroup_scanner scan;
	struct cgroup *to;
};
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/* bits in struct cpuset flags field */
typedef enum {
	CS_CPU_EXCLUSIVE,
	CS_MEM_EXCLUSIVE,
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	CS_MEM_HARDWALL,
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	CS_MEMORY_MIGRATE,
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	CS_SCHED_LOAD_BALANCE,
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	CS_SPREAD_PAGE,
	CS_SPREAD_SLAB,
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} cpuset_flagbits_t;

/* convenient tests for these bits */
static inline int is_cpu_exclusive(const struct cpuset *cs)
{
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	return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
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}

static inline int is_mem_exclusive(const struct cpuset *cs)
{
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	return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
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}

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static inline int is_mem_hardwall(const struct cpuset *cs)
{
	return test_bit(CS_MEM_HARDWALL, &cs->flags);
}

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static inline int is_sched_load_balance(const struct cpuset *cs)
{
	return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
}

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static inline int is_memory_migrate(const struct cpuset *cs)
{
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	return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
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}

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static inline int is_spread_page(const struct cpuset *cs)
{
	return test_bit(CS_SPREAD_PAGE, &cs->flags);
}

static inline int is_spread_slab(const struct cpuset *cs)
{
	return test_bit(CS_SPREAD_SLAB, &cs->flags);
}

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/*
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 * Increment this integer everytime any cpuset changes its
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 * mems_allowed value.  Users of cpusets can track this generation
 * number, and avoid having to lock and reload mems_allowed unless
 * the cpuset they're using changes generation.
 *
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 * A single, global generation is needed because cpuset_attach_task() could
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 * reattach a task to a different cpuset, which must not have its
 * generation numbers aliased with those of that tasks previous cpuset.
 *
 * Generations are needed for mems_allowed because one task cannot
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 * modify another's memory placement.  So we must enable every task,
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 * on every visit to __alloc_pages(), to efficiently check whether
 * its current->cpuset->mems_allowed has changed, requiring an update
 * of its current->mems_allowed.
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 *
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 * Since writes to cpuset_mems_generation are guarded by the cgroup lock
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 * there is no need to mark it atomic.
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 */
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static int cpuset_mems_generation;
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static struct cpuset top_cpuset = {
	.flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
	.cpus_allowed = CPU_MASK_ALL,
	.mems_allowed = NODE_MASK_ALL,
};

/*
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 * There are two global mutexes guarding cpuset structures.  The first
 * is the main control groups cgroup_mutex, accessed via
 * cgroup_lock()/cgroup_unlock().  The second is the cpuset-specific
 * callback_mutex, below. They can nest.  It is ok to first take
 * cgroup_mutex, then nest callback_mutex.  We also require taking
 * task_lock() when dereferencing a task's cpuset pointer.  See "The
 * task_lock() exception", at the end of this comment.
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 *
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 * A task must hold both mutexes to modify cpusets.  If a task
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 * holds cgroup_mutex, then it blocks others wanting that mutex,
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 * ensuring that it is the only task able to also acquire callback_mutex
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 * and be able to modify cpusets.  It can perform various checks on
 * the cpuset structure first, knowing nothing will change.  It can
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 * also allocate memory while just holding cgroup_mutex.  While it is
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 * performing these checks, various callback routines can briefly
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 * acquire callback_mutex to query cpusets.  Once it is ready to make
 * the changes, it takes callback_mutex, blocking everyone else.
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 *
 * Calls to the kernel memory allocator can not be made while holding
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 * callback_mutex, as that would risk double tripping on callback_mutex
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 * from one of the callbacks into the cpuset code from within
 * __alloc_pages().
 *
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 * If a task is only holding callback_mutex, then it has read-only
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 * access to cpusets.
 *
 * The task_struct fields mems_allowed and mems_generation may only
 * be accessed in the context of that task, so require no locks.
 *
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 * The cpuset_common_file_read() handlers only hold callback_mutex across
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 * small pieces of code, such as when reading out possibly multi-word
 * cpumasks and nodemasks.
 *
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 * Accessing a task's cpuset should be done in accordance with the
 * guidelines for accessing subsystem state in kernel/cgroup.c
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 */

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static DEFINE_MUTEX(callback_mutex);
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/*
 * cpuset_buffer_lock protects both the cpuset_name and cpuset_nodelist
 * buffers.  They are statically allocated to prevent using excess stack
 * when calling cpuset_print_task_mems_allowed().
 */
#define CPUSET_NAME_LEN		(128)
#define	CPUSET_NODELIST_LEN	(256)
static char cpuset_name[CPUSET_NAME_LEN];
static char cpuset_nodelist[CPUSET_NODELIST_LEN];
static DEFINE_SPINLOCK(cpuset_buffer_lock);

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/*
 * This is ugly, but preserves the userspace API for existing cpuset
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 * users. If someone tries to mount the "cpuset" filesystem, we
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 * silently switch it to mount "cgroup" instead
 */
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static int cpuset_get_sb(struct file_system_type *fs_type,
			 int flags, const char *unused_dev_name,
			 void *data, struct vfsmount *mnt)
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{
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	struct file_system_type *cgroup_fs = get_fs_type("cgroup");
	int ret = -ENODEV;
	if (cgroup_fs) {
		char mountopts[] =
			"cpuset,noprefix,"
			"release_agent=/sbin/cpuset_release_agent";
		ret = cgroup_fs->get_sb(cgroup_fs, flags,
					   unused_dev_name, mountopts, mnt);
		put_filesystem(cgroup_fs);
	}
	return ret;
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}

static struct file_system_type cpuset_fs_type = {
	.name = "cpuset",
	.get_sb = cpuset_get_sb,
};

/*
 * Return in *pmask the portion of a cpusets's cpus_allowed that
 * are online.  If none are online, walk up the cpuset hierarchy
 * until we find one that does have some online cpus.  If we get
 * all the way to the top and still haven't found any online cpus,
 * return cpu_online_map.  Or if passed a NULL cs from an exit'ing
 * task, return cpu_online_map.
 *
 * One way or another, we guarantee to return some non-empty subset
 * of cpu_online_map.
 *
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 * Call with callback_mutex held.
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 */

static void guarantee_online_cpus(const struct cpuset *cs, cpumask_t *pmask)
{
	while (cs && !cpus_intersects(cs->cpus_allowed, cpu_online_map))
		cs = cs->parent;
	if (cs)
		cpus_and(*pmask, cs->cpus_allowed, cpu_online_map);
	else
		*pmask = cpu_online_map;
	BUG_ON(!cpus_intersects(*pmask, cpu_online_map));
}

/*
 * Return in *pmask the portion of a cpusets's mems_allowed that
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 * are online, with memory.  If none are online with memory, walk
 * up the cpuset hierarchy until we find one that does have some
 * online mems.  If we get all the way to the top and still haven't
 * found any online mems, return node_states[N_HIGH_MEMORY].
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 *
 * One way or another, we guarantee to return some non-empty subset
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 * of node_states[N_HIGH_MEMORY].
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 *
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 * Call with callback_mutex held.
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 */

static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask)
{
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	while (cs && !nodes_intersects(cs->mems_allowed,
					node_states[N_HIGH_MEMORY]))
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		cs = cs->parent;
	if (cs)
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		nodes_and(*pmask, cs->mems_allowed,
					node_states[N_HIGH_MEMORY]);
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	else
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		*pmask = node_states[N_HIGH_MEMORY];
	BUG_ON(!nodes_intersects(*pmask, node_states[N_HIGH_MEMORY]));
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}

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/**
 * cpuset_update_task_memory_state - update task memory placement
 *
 * If the current tasks cpusets mems_allowed changed behind our
 * backs, update current->mems_allowed, mems_generation and task NUMA
 * mempolicy to the new value.
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 *
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 * Task mempolicy is updated by rebinding it relative to the
 * current->cpuset if a task has its memory placement changed.
 * Do not call this routine if in_interrupt().
 *
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 * Call without callback_mutex or task_lock() held.  May be
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 * called with or without cgroup_mutex held.  Thanks in part to
 * 'the_top_cpuset_hack', the task's cpuset pointer will never
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 * be NULL.  This routine also might acquire callback_mutex during
 * call.
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 *
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 * Reading current->cpuset->mems_generation doesn't need task_lock
 * to guard the current->cpuset derefence, because it is guarded
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 * from concurrent freeing of current->cpuset using RCU.
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 *
 * The rcu_dereference() is technically probably not needed,
 * as I don't actually mind if I see a new cpuset pointer but
 * an old value of mems_generation.  However this really only
 * matters on alpha systems using cpusets heavily.  If I dropped
 * that rcu_dereference(), it would save them a memory barrier.
 * For all other arch's, rcu_dereference is a no-op anyway, and for
 * alpha systems not using cpusets, another planned optimization,
 * avoiding the rcu critical section for tasks in the root cpuset
 * which is statically allocated, so can't vanish, will make this
 * irrelevant.  Better to use RCU as intended, than to engage in
 * some cute trick to save a memory barrier that is impossible to
 * test, for alpha systems using cpusets heavily, which might not
 * even exist.
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 *
 * This routine is needed to update the per-task mems_allowed data,
 * within the tasks context, when it is trying to allocate memory
 * (in various mm/mempolicy.c routines) and notices that some other
 * task has been modifying its cpuset.
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 */

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void cpuset_update_task_memory_state(void)
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{
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	int my_cpusets_mem_gen;
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	struct task_struct *tsk = current;
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	struct cpuset *cs;
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	rcu_read_lock();
	my_cpusets_mem_gen = task_cs(tsk)->mems_generation;
	rcu_read_unlock();
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	if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) {
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		mutex_lock(&callback_mutex);
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		task_lock(tsk);
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		cs = task_cs(tsk); /* Maybe changed when task not locked */
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		guarantee_online_mems(cs, &tsk->mems_allowed);
		tsk->cpuset_mems_generation = cs->mems_generation;
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		if (is_spread_page(cs))
			tsk->flags |= PF_SPREAD_PAGE;
		else
			tsk->flags &= ~PF_SPREAD_PAGE;
		if (is_spread_slab(cs))
			tsk->flags |= PF_SPREAD_SLAB;
		else
			tsk->flags &= ~PF_SPREAD_SLAB;
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		task_unlock(tsk);
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		mutex_unlock(&callback_mutex);
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		mpol_rebind_task(tsk, &tsk->mems_allowed);
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	}
}

/*
 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
 *
 * One cpuset is a subset of another if all its allowed CPUs and
 * Memory Nodes are a subset of the other, and its exclusive flags
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 * are only set if the other's are set.  Call holding cgroup_mutex.
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 */

static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
{
	return	cpus_subset(p->cpus_allowed, q->cpus_allowed) &&
		nodes_subset(p->mems_allowed, q->mems_allowed) &&
		is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
		is_mem_exclusive(p) <= is_mem_exclusive(q);
}

/*
 * validate_change() - Used to validate that any proposed cpuset change
 *		       follows the structural rules for cpusets.
 *
 * If we replaced the flag and mask values of the current cpuset
 * (cur) with those values in the trial cpuset (trial), would
 * our various subset and exclusive rules still be valid?  Presumes
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 * cgroup_mutex held.
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 *
 * 'cur' is the address of an actual, in-use cpuset.  Operations
 * such as list traversal that depend on the actual address of the
 * cpuset in the list must use cur below, not trial.
 *
 * 'trial' is the address of bulk structure copy of cur, with
 * perhaps one or more of the fields cpus_allowed, mems_allowed,
 * or flags changed to new, trial values.
 *
 * Return 0 if valid, -errno if not.
 */

static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
{
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	struct cgroup *cont;
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	struct cpuset *c, *par;

	/* Each of our child cpusets must be a subset of us */
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	list_for_each_entry(cont, &cur->css.cgroup->children, sibling) {
		if (!is_cpuset_subset(cgroup_cs(cont), trial))
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			return -EBUSY;
	}

	/* Remaining checks don't apply to root cpuset */
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	if (cur == &top_cpuset)
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		return 0;

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	par = cur->parent;

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	/* We must be a subset of our parent cpuset */
	if (!is_cpuset_subset(trial, par))
		return -EACCES;

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	/*
	 * If either I or some sibling (!= me) is exclusive, we can't
	 * overlap
	 */
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	list_for_each_entry(cont, &par->css.cgroup->children, sibling) {
		c = cgroup_cs(cont);
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		if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
		    c != cur &&
		    cpus_intersects(trial->cpus_allowed, c->cpus_allowed))
			return -EINVAL;
		if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
		    c != cur &&
		    nodes_intersects(trial->mems_allowed, c->mems_allowed))
			return -EINVAL;
	}

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	/* Cpusets with tasks can't have empty cpus_allowed or mems_allowed */
	if (cgroup_task_count(cur->css.cgroup)) {
		if (cpus_empty(trial->cpus_allowed) ||
		    nodes_empty(trial->mems_allowed)) {
			return -ENOSPC;
		}
	}

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	return 0;
}

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/*
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 * Helper routine for generate_sched_domains().
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 * Do cpusets a, b have overlapping cpus_allowed masks?
 */
static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
{
	return cpus_intersects(a->cpus_allowed, b->cpus_allowed);
}

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static void
update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
{
	if (dattr->relax_domain_level < c->relax_domain_level)
		dattr->relax_domain_level = c->relax_domain_level;
	return;
}

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static void
update_domain_attr_tree(struct sched_domain_attr *dattr, struct cpuset *c)
{
	LIST_HEAD(q);

	list_add(&c->stack_list, &q);
	while (!list_empty(&q)) {
		struct cpuset *cp;
		struct cgroup *cont;
		struct cpuset *child;

		cp = list_first_entry(&q, struct cpuset, stack_list);
		list_del(q.next);

		if (cpus_empty(cp->cpus_allowed))
			continue;

		if (is_sched_load_balance(cp))
			update_domain_attr(dattr, cp);

		list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
			child = cgroup_cs(cont);
			list_add_tail(&child->stack_list, &q);
		}
	}
}

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/*
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 * generate_sched_domains()
 *
 * This function builds a partial partition of the systems CPUs
 * A 'partial partition' is a set of non-overlapping subsets whose
 * union is a subset of that set.
 * The output of this function needs to be passed to kernel/sched.c
 * partition_sched_domains() routine, which will rebuild the scheduler's
 * load balancing domains (sched domains) as specified by that partial
 * partition.
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 *
 * See "What is sched_load_balance" in Documentation/cpusets.txt
 * for a background explanation of this.
 *
 * Does not return errors, on the theory that the callers of this
 * routine would rather not worry about failures to rebuild sched
 * domains when operating in the severe memory shortage situations
 * that could cause allocation failures below.
 *
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 * Must be called with cgroup_lock held.
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 *
 * The three key local variables below are:
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 *    q  - a linked-list queue of cpuset pointers, used to implement a
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 *	   top-down scan of all cpusets.  This scan loads a pointer
 *	   to each cpuset marked is_sched_load_balance into the
 *	   array 'csa'.  For our purposes, rebuilding the schedulers
 *	   sched domains, we can ignore !is_sched_load_balance cpusets.
 *  csa  - (for CpuSet Array) Array of pointers to all the cpusets
 *	   that need to be load balanced, for convenient iterative
 *	   access by the subsequent code that finds the best partition,
 *	   i.e the set of domains (subsets) of CPUs such that the
 *	   cpus_allowed of every cpuset marked is_sched_load_balance
 *	   is a subset of one of these domains, while there are as
 *	   many such domains as possible, each as small as possible.
 * doms  - Conversion of 'csa' to an array of cpumasks, for passing to
 *	   the kernel/sched.c routine partition_sched_domains() in a
 *	   convenient format, that can be easily compared to the prior
 *	   value to determine what partition elements (sched domains)
 *	   were changed (added or removed.)
 *
 * Finding the best partition (set of domains):
 *	The triple nested loops below over i, j, k scan over the
 *	load balanced cpusets (using the array of cpuset pointers in
 *	csa[]) looking for pairs of cpusets that have overlapping
 *	cpus_allowed, but which don't have the same 'pn' partition
 *	number and gives them in the same partition number.  It keeps
 *	looping on the 'restart' label until it can no longer find
 *	any such pairs.
 *
 *	The union of the cpus_allowed masks from the set of
 *	all cpusets having the same 'pn' value then form the one
 *	element of the partition (one sched domain) to be passed to
 *	partition_sched_domains().
 */
584 585
static int generate_sched_domains(cpumask_t **domains,
			struct sched_domain_attr **attributes)
P
Paul Jackson 已提交
586
{
587
	LIST_HEAD(q);		/* queue of cpusets to be scanned */
P
Paul Jackson 已提交
588 589 590 591 592
	struct cpuset *cp;	/* scans q */
	struct cpuset **csa;	/* array of all cpuset ptrs */
	int csn;		/* how many cpuset ptrs in csa so far */
	int i, j, k;		/* indices for partition finding loops */
	cpumask_t *doms;	/* resulting partition; i.e. sched domains */
593
	struct sched_domain_attr *dattr;  /* attributes for custom domains */
594
	int ndoms = 0;		/* number of sched domains in result */
P
Paul Jackson 已提交
595 596 597
	int nslot;		/* next empty doms[] cpumask_t slot */

	doms = NULL;
598
	dattr = NULL;
599
	csa = NULL;
P
Paul Jackson 已提交
600 601 602 603 604

	/* Special case for the 99% of systems with one, full, sched domain */
	if (is_sched_load_balance(&top_cpuset)) {
		doms = kmalloc(sizeof(cpumask_t), GFP_KERNEL);
		if (!doms)
605 606
			goto done;

607 608 609
		dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
		if (dattr) {
			*dattr = SD_ATTR_INIT;
610
			update_domain_attr_tree(dattr, &top_cpuset);
611
		}
P
Paul Jackson 已提交
612
		*doms = top_cpuset.cpus_allowed;
613 614 615

		ndoms = 1;
		goto done;
P
Paul Jackson 已提交
616 617 618 619 620 621 622
	}

	csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL);
	if (!csa)
		goto done;
	csn = 0;

623 624
	list_add(&top_cpuset.stack_list, &q);
	while (!list_empty(&q)) {
P
Paul Jackson 已提交
625 626
		struct cgroup *cont;
		struct cpuset *child;   /* scans child cpusets of cp */
627

628 629 630
		cp = list_first_entry(&q, struct cpuset, stack_list);
		list_del(q.next);

631 632 633
		if (cpus_empty(cp->cpus_allowed))
			continue;

634 635 636 637 638 639 640
		/*
		 * All child cpusets contain a subset of the parent's cpus, so
		 * just skip them, and then we call update_domain_attr_tree()
		 * to calc relax_domain_level of the corresponding sched
		 * domain.
		 */
		if (is_sched_load_balance(cp)) {
P
Paul Jackson 已提交
641
			csa[csn++] = cp;
642 643
			continue;
		}
644

P
Paul Jackson 已提交
645 646
		list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
			child = cgroup_cs(cont);
647
			list_add_tail(&child->stack_list, &q);
P
Paul Jackson 已提交
648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677
		}
  	}

	for (i = 0; i < csn; i++)
		csa[i]->pn = i;
	ndoms = csn;

restart:
	/* Find the best partition (set of sched domains) */
	for (i = 0; i < csn; i++) {
		struct cpuset *a = csa[i];
		int apn = a->pn;

		for (j = 0; j < csn; j++) {
			struct cpuset *b = csa[j];
			int bpn = b->pn;

			if (apn != bpn && cpusets_overlap(a, b)) {
				for (k = 0; k < csn; k++) {
					struct cpuset *c = csa[k];

					if (c->pn == bpn)
						c->pn = apn;
				}
				ndoms--;	/* one less element */
				goto restart;
			}
		}
	}

678 679 680 681
	/*
	 * Now we know how many domains to create.
	 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
	 */
P
Paul Jackson 已提交
682
	doms = kmalloc(ndoms * sizeof(cpumask_t), GFP_KERNEL);
683
	if (!doms)
684 685 686 687 688 689
		goto done;

	/*
	 * The rest of the code, including the scheduler, can deal with
	 * dattr==NULL case. No need to abort if alloc fails.
	 */
690
	dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
P
Paul Jackson 已提交
691 692 693

	for (nslot = 0, i = 0; i < csn; i++) {
		struct cpuset *a = csa[i];
694
		cpumask_t *dp;
P
Paul Jackson 已提交
695 696
		int apn = a->pn;

697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712
		if (apn < 0) {
			/* Skip completed partitions */
			continue;
		}

		dp = doms + nslot;

		if (nslot == ndoms) {
			static int warnings = 10;
			if (warnings) {
				printk(KERN_WARNING
				 "rebuild_sched_domains confused:"
				  " nslot %d, ndoms %d, csn %d, i %d,"
				  " apn %d\n",
				  nslot, ndoms, csn, i, apn);
				warnings--;
P
Paul Jackson 已提交
713
			}
714 715
			continue;
		}
P
Paul Jackson 已提交
716

717 718 719 720 721 722 723 724 725 726 727 728 729
		cpus_clear(*dp);
		if (dattr)
			*(dattr + nslot) = SD_ATTR_INIT;
		for (j = i; j < csn; j++) {
			struct cpuset *b = csa[j];

			if (apn == b->pn) {
				cpus_or(*dp, *dp, b->cpus_allowed);
				if (dattr)
					update_domain_attr_tree(dattr + nslot, b);

				/* Done with this partition */
				b->pn = -1;
P
Paul Jackson 已提交
730 731
			}
		}
732
		nslot++;
P
Paul Jackson 已提交
733 734 735
	}
	BUG_ON(nslot != ndoms);

736 737 738
done:
	kfree(csa);

739 740 741 742 743 744 745
	/*
	 * Fallback to the default domain if kmalloc() failed.
	 * See comments in partition_sched_domains().
	 */
	if (doms == NULL)
		ndoms = 1;

746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766
	*domains    = doms;
	*attributes = dattr;
	return ndoms;
}

/*
 * Rebuild scheduler domains.
 *
 * Call with neither cgroup_mutex held nor within get_online_cpus().
 * Takes both cgroup_mutex and get_online_cpus().
 *
 * Cannot be directly called from cpuset code handling changes
 * to the cpuset pseudo-filesystem, because it cannot be called
 * from code that already holds cgroup_mutex.
 */
static void do_rebuild_sched_domains(struct work_struct *unused)
{
	struct sched_domain_attr *attr;
	cpumask_t *doms;
	int ndoms;

767
	get_online_cpus();
768 769 770 771 772 773 774 775 776

	/* Generate domain masks and attrs */
	cgroup_lock();
	ndoms = generate_sched_domains(&doms, &attr);
	cgroup_unlock();

	/* Have scheduler rebuild the domains */
	partition_sched_domains(ndoms, doms, attr);

777
	put_online_cpus();
778
}
P
Paul Jackson 已提交
779

780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817
static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains);

/*
 * Rebuild scheduler domains, asynchronously via workqueue.
 *
 * If the flag 'sched_load_balance' of any cpuset with non-empty
 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
 * which has that flag enabled, or if any cpuset with a non-empty
 * 'cpus' is removed, then call this routine to rebuild the
 * scheduler's dynamic sched domains.
 *
 * The rebuild_sched_domains() and partition_sched_domains()
 * routines must nest cgroup_lock() inside get_online_cpus(),
 * but such cpuset changes as these must nest that locking the
 * other way, holding cgroup_lock() for much of the code.
 *
 * So in order to avoid an ABBA deadlock, the cpuset code handling
 * these user changes delegates the actual sched domain rebuilding
 * to a separate workqueue thread, which ends up processing the
 * above do_rebuild_sched_domains() function.
 */
static void async_rebuild_sched_domains(void)
{
	schedule_work(&rebuild_sched_domains_work);
}

/*
 * Accomplishes the same scheduler domain rebuild as the above
 * async_rebuild_sched_domains(), however it directly calls the
 * rebuild routine synchronously rather than calling it via an
 * asynchronous work thread.
 *
 * This can only be called from code that is not holding
 * cgroup_mutex (not nested in a cgroup_lock() call.)
 */
void rebuild_sched_domains(void)
{
	do_rebuild_sched_domains(NULL);
P
Paul Jackson 已提交
818 819
}

C
Cliff Wickman 已提交
820 821 822 823 824
/**
 * cpuset_test_cpumask - test a task's cpus_allowed versus its cpuset's
 * @tsk: task to test
 * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
 *
825
 * Call with cgroup_mutex held.  May take callback_mutex during call.
C
Cliff Wickman 已提交
826 827 828
 * Called for each task in a cgroup by cgroup_scan_tasks().
 * Return nonzero if this tasks's cpus_allowed mask should be changed (in other
 * words, if its mask is not equal to its cpuset's mask).
829
 */
830 831
static int cpuset_test_cpumask(struct task_struct *tsk,
			       struct cgroup_scanner *scan)
C
Cliff Wickman 已提交
832 833 834 835
{
	return !cpus_equal(tsk->cpus_allowed,
			(cgroup_cs(scan->cg))->cpus_allowed);
}
836

C
Cliff Wickman 已提交
837 838 839 840 841 842 843 844 845 846 847
/**
 * cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's
 * @tsk: task to test
 * @scan: struct cgroup_scanner containing the cgroup of the task
 *
 * Called by cgroup_scan_tasks() for each task in a cgroup whose
 * cpus_allowed mask needs to be changed.
 *
 * We don't need to re-check for the cgroup/cpuset membership, since we're
 * holding cgroup_lock() at this point.
 */
848 849
static void cpuset_change_cpumask(struct task_struct *tsk,
				  struct cgroup_scanner *scan)
C
Cliff Wickman 已提交
850
{
851
	set_cpus_allowed_ptr(tsk, &((cgroup_cs(scan->cg))->cpus_allowed));
C
Cliff Wickman 已提交
852 853
}

854 855 856
/**
 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
857
 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
858 859 860 861 862 863
 *
 * Called with cgroup_mutex held
 *
 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
 * calling callback functions for each.
 *
864 865
 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
 * if @heap != NULL.
866
 */
867
static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap)
868 869 870 871 872 873
{
	struct cgroup_scanner scan;

	scan.cg = cs->css.cgroup;
	scan.test_task = cpuset_test_cpumask;
	scan.process_task = cpuset_change_cpumask;
874 875
	scan.heap = heap;
	cgroup_scan_tasks(&scan);
876 877
}

C
Cliff Wickman 已提交
878 879 880 881 882
/**
 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
 * @cs: the cpuset to consider
 * @buf: buffer of cpu numbers written to this cpuset
 */
883
static int update_cpumask(struct cpuset *cs, const char *buf)
L
Linus Torvalds 已提交
884
{
885
	struct ptr_heap heap;
L
Linus Torvalds 已提交
886
	struct cpuset trialcs;
C
Cliff Wickman 已提交
887 888
	int retval;
	int is_load_balanced;
L
Linus Torvalds 已提交
889

890 891 892 893
	/* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */
	if (cs == &top_cpuset)
		return -EACCES;

L
Linus Torvalds 已提交
894
	trialcs = *cs;
895 896

	/*
897
	 * An empty cpus_allowed is ok only if the cpuset has no tasks.
898 899 900
	 * Since cpulist_parse() fails on an empty mask, we special case
	 * that parsing.  The validate_change() call ensures that cpusets
	 * with tasks have cpus.
901
	 */
902
	if (!*buf) {
903 904
		cpus_clear(trialcs.cpus_allowed);
	} else {
905
		retval = cpulist_parse(buf, &trialcs.cpus_allowed);
906 907
		if (retval < 0)
			return retval;
908 909 910

		if (!cpus_subset(trialcs.cpus_allowed, cpu_online_map))
			return -EINVAL;
911
	}
L
Linus Torvalds 已提交
912
	retval = validate_change(cs, &trialcs);
913 914
	if (retval < 0)
		return retval;
P
Paul Jackson 已提交
915

P
Paul Menage 已提交
916 917 918
	/* Nothing to do if the cpus didn't change */
	if (cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed))
		return 0;
C
Cliff Wickman 已提交
919

920 921 922 923
	retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
	if (retval)
		return retval;

P
Paul Jackson 已提交
924 925
	is_load_balanced = is_sched_load_balance(&trialcs);

926
	mutex_lock(&callback_mutex);
927
	cs->cpus_allowed = trialcs.cpus_allowed;
928
	mutex_unlock(&callback_mutex);
P
Paul Jackson 已提交
929

P
Paul Menage 已提交
930 931
	/*
	 * Scan tasks in the cpuset, and update the cpumasks of any
C
Cliff Wickman 已提交
932
	 * that need an update.
P
Paul Menage 已提交
933
	 */
934 935 936
	update_tasks_cpumask(cs, &heap);

	heap_free(&heap);
C
Cliff Wickman 已提交
937

P
Paul Menage 已提交
938
	if (is_load_balanced)
939
		async_rebuild_sched_domains();
940
	return 0;
L
Linus Torvalds 已提交
941 942
}

943 944 945 946 947 948 949 950
/*
 * cpuset_migrate_mm
 *
 *    Migrate memory region from one set of nodes to another.
 *
 *    Temporarilly set tasks mems_allowed to target nodes of migration,
 *    so that the migration code can allocate pages on these nodes.
 *
951
 *    Call holding cgroup_mutex, so current's cpuset won't change
952
 *    during this call, as manage_mutex holds off any cpuset_attach()
953 954
 *    calls.  Therefore we don't need to take task_lock around the
 *    call to guarantee_online_mems(), as we know no one is changing
955
 *    our task's cpuset.
956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987
 *
 *    Hold callback_mutex around the two modifications of our tasks
 *    mems_allowed to synchronize with cpuset_mems_allowed().
 *
 *    While the mm_struct we are migrating is typically from some
 *    other task, the task_struct mems_allowed that we are hacking
 *    is for our current task, which must allocate new pages for that
 *    migrating memory region.
 *
 *    We call cpuset_update_task_memory_state() before hacking
 *    our tasks mems_allowed, so that we are assured of being in
 *    sync with our tasks cpuset, and in particular, callbacks to
 *    cpuset_update_task_memory_state() from nested page allocations
 *    won't see any mismatch of our cpuset and task mems_generation
 *    values, so won't overwrite our hacked tasks mems_allowed
 *    nodemask.
 */

static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
							const nodemask_t *to)
{
	struct task_struct *tsk = current;

	cpuset_update_task_memory_state();

	mutex_lock(&callback_mutex);
	tsk->mems_allowed = *to;
	mutex_unlock(&callback_mutex);

	do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);

	mutex_lock(&callback_mutex);
988
	guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
989 990 991
	mutex_unlock(&callback_mutex);
}

992 993
static void *cpuset_being_rebound;

994 995 996 997 998 999 1000 1001 1002
/**
 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
 * @oldmem: old mems_allowed of cpuset cs
 *
 * Called with cgroup_mutex held
 * Return 0 if successful, -errno if not.
 */
static int update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem)
L
Linus Torvalds 已提交
1003
{
1004
	struct task_struct *p;
1005 1006
	struct mm_struct **mmarray;
	int i, n, ntasks;
1007
	int migrate;
1008
	int fudge;
1009
	struct cgroup_iter it;
1010
	int retval;
1011

1012
	cpuset_being_rebound = cs;		/* causes mpol_dup() rebind */
1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025

	fudge = 10;				/* spare mmarray[] slots */
	fudge += cpus_weight(cs->cpus_allowed);	/* imagine one fork-bomb/cpu */
	retval = -ENOMEM;

	/*
	 * Allocate mmarray[] to hold mm reference for each task
	 * in cpuset cs.  Can't kmalloc GFP_KERNEL while holding
	 * tasklist_lock.  We could use GFP_ATOMIC, but with a
	 * few more lines of code, we can retry until we get a big
	 * enough mmarray[] w/o using GFP_ATOMIC.
	 */
	while (1) {
1026
		ntasks = cgroup_task_count(cs->css.cgroup);  /* guess */
1027 1028 1029 1030
		ntasks += fudge;
		mmarray = kmalloc(ntasks * sizeof(*mmarray), GFP_KERNEL);
		if (!mmarray)
			goto done;
1031
		read_lock(&tasklist_lock);		/* block fork */
1032
		if (cgroup_task_count(cs->css.cgroup) <= ntasks)
1033
			break;				/* got enough */
1034
		read_unlock(&tasklist_lock);		/* try again */
1035 1036 1037 1038 1039 1040
		kfree(mmarray);
	}

	n = 0;

	/* Load up mmarray[] with mm reference for each task in cpuset. */
1041 1042
	cgroup_iter_start(cs->css.cgroup, &it);
	while ((p = cgroup_iter_next(cs->css.cgroup, &it))) {
1043 1044 1045 1046 1047
		struct mm_struct *mm;

		if (n >= ntasks) {
			printk(KERN_WARNING
				"Cpuset mempolicy rebind incomplete.\n");
1048
			break;
1049 1050 1051 1052 1053
		}
		mm = get_task_mm(p);
		if (!mm)
			continue;
		mmarray[n++] = mm;
1054 1055
	}
	cgroup_iter_end(cs->css.cgroup, &it);
1056
	read_unlock(&tasklist_lock);
1057 1058 1059 1060 1061 1062

	/*
	 * Now that we've dropped the tasklist spinlock, we can
	 * rebind the vma mempolicies of each mm in mmarray[] to their
	 * new cpuset, and release that mm.  The mpol_rebind_mm()
	 * call takes mmap_sem, which we couldn't take while holding
1063
	 * tasklist_lock.  Forks can happen again now - the mpol_dup()
1064 1065
	 * cpuset_being_rebound check will catch such forks, and rebind
	 * their vma mempolicies too.  Because we still hold the global
1066
	 * cgroup_mutex, we know that no other rebind effort will
1067 1068
	 * be contending for the global variable cpuset_being_rebound.
	 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1069
	 * is idempotent.  Also migrate pages in each mm to new nodes.
1070
	 */
1071
	migrate = is_memory_migrate(cs);
1072 1073 1074 1075
	for (i = 0; i < n; i++) {
		struct mm_struct *mm = mmarray[i];

		mpol_rebind_mm(mm, &cs->mems_allowed);
1076
		if (migrate)
1077
			cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
1078 1079 1080
		mmput(mm);
	}

1081
	/* We're done rebinding vmas to this cpuset's new mems_allowed. */
1082
	kfree(mmarray);
1083
	cpuset_being_rebound = NULL;
1084
	retval = 0;
1085
done:
L
Linus Torvalds 已提交
1086 1087 1088
	return retval;
}

1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152
/*
 * Handle user request to change the 'mems' memory placement
 * of a cpuset.  Needs to validate the request, update the
 * cpusets mems_allowed and mems_generation, and for each
 * task in the cpuset, rebind any vma mempolicies and if
 * the cpuset is marked 'memory_migrate', migrate the tasks
 * pages to the new memory.
 *
 * Call with cgroup_mutex held.  May take callback_mutex during call.
 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
 * lock each such tasks mm->mmap_sem, scan its vma's and rebind
 * their mempolicies to the cpusets new mems_allowed.
 */
static int update_nodemask(struct cpuset *cs, const char *buf)
{
	struct cpuset trialcs;
	nodemask_t oldmem;
	int retval;

	/*
	 * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
	 * it's read-only
	 */
	if (cs == &top_cpuset)
		return -EACCES;

	trialcs = *cs;

	/*
	 * An empty mems_allowed is ok iff there are no tasks in the cpuset.
	 * Since nodelist_parse() fails on an empty mask, we special case
	 * that parsing.  The validate_change() call ensures that cpusets
	 * with tasks have memory.
	 */
	if (!*buf) {
		nodes_clear(trialcs.mems_allowed);
	} else {
		retval = nodelist_parse(buf, trialcs.mems_allowed);
		if (retval < 0)
			goto done;

		if (!nodes_subset(trialcs.mems_allowed,
				node_states[N_HIGH_MEMORY]))
			return -EINVAL;
	}
	oldmem = cs->mems_allowed;
	if (nodes_equal(oldmem, trialcs.mems_allowed)) {
		retval = 0;		/* Too easy - nothing to do */
		goto done;
	}
	retval = validate_change(cs, &trialcs);
	if (retval < 0)
		goto done;

	mutex_lock(&callback_mutex);
	cs->mems_allowed = trialcs.mems_allowed;
	cs->mems_generation = cpuset_mems_generation++;
	mutex_unlock(&callback_mutex);

	retval = update_tasks_nodemask(cs, &oldmem);
done:
	return retval;
}

1153 1154 1155 1156 1157
int current_cpuset_is_being_rebound(void)
{
	return task_cs(current) == cpuset_being_rebound;
}

1158
static int update_relax_domain_level(struct cpuset *cs, s64 val)
1159
{
1160 1161
	if (val < -1 || val >= SD_LV_MAX)
		return -EINVAL;
1162 1163 1164

	if (val != cs->relax_domain_level) {
		cs->relax_domain_level = val;
1165
		if (!cpus_empty(cs->cpus_allowed) && is_sched_load_balance(cs))
1166
			async_rebuild_sched_domains();
1167 1168 1169 1170 1171
	}

	return 0;
}

L
Linus Torvalds 已提交
1172 1173
/*
 * update_flag - read a 0 or a 1 in a file and update associated flag
1174 1175 1176
 * bit:		the bit to update (see cpuset_flagbits_t)
 * cs:		the cpuset to update
 * turning_on: 	whether the flag is being set or cleared
1177
 *
1178
 * Call with cgroup_mutex held.
L
Linus Torvalds 已提交
1179 1180
 */

1181 1182
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
		       int turning_on)
L
Linus Torvalds 已提交
1183 1184
{
	struct cpuset trialcs;
1185
	int err;
R
Rakib Mullick 已提交
1186
	int balance_flag_changed;
L
Linus Torvalds 已提交
1187 1188 1189 1190 1191 1192 1193 1194

	trialcs = *cs;
	if (turning_on)
		set_bit(bit, &trialcs.flags);
	else
		clear_bit(bit, &trialcs.flags);

	err = validate_change(cs, &trialcs);
1195 1196
	if (err < 0)
		return err;
P
Paul Jackson 已提交
1197 1198 1199 1200

	balance_flag_changed = (is_sched_load_balance(cs) !=
		 			is_sched_load_balance(&trialcs));

1201
	mutex_lock(&callback_mutex);
1202
	cs->flags = trialcs.flags;
1203
	mutex_unlock(&callback_mutex);
1204

R
Rakib Mullick 已提交
1205
	if (!cpus_empty(trialcs.cpus_allowed) && balance_flag_changed)
1206
		async_rebuild_sched_domains();
P
Paul Jackson 已提交
1207

1208
	return 0;
L
Linus Torvalds 已提交
1209 1210
}

1211
/*
A
Adrian Bunk 已提交
1212
 * Frequency meter - How fast is some event occurring?
1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308
 *
 * These routines manage a digitally filtered, constant time based,
 * event frequency meter.  There are four routines:
 *   fmeter_init() - initialize a frequency meter.
 *   fmeter_markevent() - called each time the event happens.
 *   fmeter_getrate() - returns the recent rate of such events.
 *   fmeter_update() - internal routine used to update fmeter.
 *
 * A common data structure is passed to each of these routines,
 * which is used to keep track of the state required to manage the
 * frequency meter and its digital filter.
 *
 * The filter works on the number of events marked per unit time.
 * The filter is single-pole low-pass recursive (IIR).  The time unit
 * is 1 second.  Arithmetic is done using 32-bit integers scaled to
 * simulate 3 decimal digits of precision (multiplied by 1000).
 *
 * With an FM_COEF of 933, and a time base of 1 second, the filter
 * has a half-life of 10 seconds, meaning that if the events quit
 * happening, then the rate returned from the fmeter_getrate()
 * will be cut in half each 10 seconds, until it converges to zero.
 *
 * It is not worth doing a real infinitely recursive filter.  If more
 * than FM_MAXTICKS ticks have elapsed since the last filter event,
 * just compute FM_MAXTICKS ticks worth, by which point the level
 * will be stable.
 *
 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
 * arithmetic overflow in the fmeter_update() routine.
 *
 * Given the simple 32 bit integer arithmetic used, this meter works
 * best for reporting rates between one per millisecond (msec) and
 * one per 32 (approx) seconds.  At constant rates faster than one
 * per msec it maxes out at values just under 1,000,000.  At constant
 * rates between one per msec, and one per second it will stabilize
 * to a value N*1000, where N is the rate of events per second.
 * At constant rates between one per second and one per 32 seconds,
 * it will be choppy, moving up on the seconds that have an event,
 * and then decaying until the next event.  At rates slower than
 * about one in 32 seconds, it decays all the way back to zero between
 * each event.
 */

#define FM_COEF 933		/* coefficient for half-life of 10 secs */
#define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
#define FM_MAXCNT 1000000	/* limit cnt to avoid overflow */
#define FM_SCALE 1000		/* faux fixed point scale */

/* Initialize a frequency meter */
static void fmeter_init(struct fmeter *fmp)
{
	fmp->cnt = 0;
	fmp->val = 0;
	fmp->time = 0;
	spin_lock_init(&fmp->lock);
}

/* Internal meter update - process cnt events and update value */
static void fmeter_update(struct fmeter *fmp)
{
	time_t now = get_seconds();
	time_t ticks = now - fmp->time;

	if (ticks == 0)
		return;

	ticks = min(FM_MAXTICKS, ticks);
	while (ticks-- > 0)
		fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
	fmp->time = now;

	fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
	fmp->cnt = 0;
}

/* Process any previous ticks, then bump cnt by one (times scale). */
static void fmeter_markevent(struct fmeter *fmp)
{
	spin_lock(&fmp->lock);
	fmeter_update(fmp);
	fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
	spin_unlock(&fmp->lock);
}

/* Process any previous ticks, then return current value. */
static int fmeter_getrate(struct fmeter *fmp)
{
	int val;

	spin_lock(&fmp->lock);
	fmeter_update(fmp);
	val = fmp->val;
	spin_unlock(&fmp->lock);
	return val;
}

1309 1310 1311
/* Protected by cgroup_lock */
static cpumask_var_t cpus_attach;

1312
/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
1313 1314
static int cpuset_can_attach(struct cgroup_subsys *ss,
			     struct cgroup *cont, struct task_struct *tsk)
L
Linus Torvalds 已提交
1315
{
1316
	struct cpuset *cs = cgroup_cs(cont);
1317
	int ret = 0;
L
Linus Torvalds 已提交
1318 1319 1320

	if (cpus_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
		return -ENOSPC;
1321

1322
	if (tsk->flags & PF_THREAD_BOUND) {
1323
		mutex_lock(&callback_mutex);
1324 1325
		if (!cpus_equal(tsk->cpus_allowed, cs->cpus_allowed))
			ret = -EINVAL;
1326 1327
		mutex_unlock(&callback_mutex);
	}
L
Linus Torvalds 已提交
1328

1329
	return ret < 0 ? ret : security_task_setscheduler(tsk, 0, NULL);
1330
}
L
Linus Torvalds 已提交
1331

1332 1333 1334 1335 1336 1337 1338 1339
static void cpuset_attach(struct cgroup_subsys *ss,
			  struct cgroup *cont, struct cgroup *oldcont,
			  struct task_struct *tsk)
{
	nodemask_t from, to;
	struct mm_struct *mm;
	struct cpuset *cs = cgroup_cs(cont);
	struct cpuset *oldcs = cgroup_cs(oldcont);
1340
	int err;
1341

1342
	if (cs == &top_cpuset) {
1343
		cpumask_copy(cpus_attach, cpu_possible_mask);
1344 1345
	} else {
		mutex_lock(&callback_mutex);
1346
		guarantee_online_cpus(cs, cpus_attach);
1347 1348
		mutex_unlock(&callback_mutex);
	}
1349
	err = set_cpus_allowed_ptr(tsk, cpus_attach);
1350 1351
	if (err)
		return;
L
Linus Torvalds 已提交
1352

1353 1354
	from = oldcs->mems_allowed;
	to = cs->mems_allowed;
1355 1356 1357
	mm = get_task_mm(tsk);
	if (mm) {
		mpol_rebind_mm(mm, &to);
1358
		if (is_memory_migrate(cs))
1359
			cpuset_migrate_mm(mm, &from, &to);
1360 1361
		mmput(mm);
	}
L
Linus Torvalds 已提交
1362 1363 1364 1365 1366
}

/* The various types of files and directories in a cpuset file system */

typedef enum {
1367
	FILE_MEMORY_MIGRATE,
L
Linus Torvalds 已提交
1368 1369 1370 1371
	FILE_CPULIST,
	FILE_MEMLIST,
	FILE_CPU_EXCLUSIVE,
	FILE_MEM_EXCLUSIVE,
1372
	FILE_MEM_HARDWALL,
P
Paul Jackson 已提交
1373
	FILE_SCHED_LOAD_BALANCE,
1374
	FILE_SCHED_RELAX_DOMAIN_LEVEL,
1375 1376
	FILE_MEMORY_PRESSURE_ENABLED,
	FILE_MEMORY_PRESSURE,
1377 1378
	FILE_SPREAD_PAGE,
	FILE_SPREAD_SLAB,
L
Linus Torvalds 已提交
1379 1380
} cpuset_filetype_t;

1381 1382 1383 1384 1385 1386
static int cpuset_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
{
	int retval = 0;
	struct cpuset *cs = cgroup_cs(cgrp);
	cpuset_filetype_t type = cft->private;

1387
	if (!cgroup_lock_live_group(cgrp))
1388 1389 1390
		return -ENODEV;

	switch (type) {
L
Linus Torvalds 已提交
1391
	case FILE_CPU_EXCLUSIVE:
1392
		retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
L
Linus Torvalds 已提交
1393 1394
		break;
	case FILE_MEM_EXCLUSIVE:
1395
		retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
L
Linus Torvalds 已提交
1396
		break;
1397 1398 1399
	case FILE_MEM_HARDWALL:
		retval = update_flag(CS_MEM_HARDWALL, cs, val);
		break;
P
Paul Jackson 已提交
1400
	case FILE_SCHED_LOAD_BALANCE:
1401
		retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1402
		break;
1403
	case FILE_MEMORY_MIGRATE:
1404
		retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1405
		break;
1406
	case FILE_MEMORY_PRESSURE_ENABLED:
1407
		cpuset_memory_pressure_enabled = !!val;
1408 1409 1410 1411
		break;
	case FILE_MEMORY_PRESSURE:
		retval = -EACCES;
		break;
1412
	case FILE_SPREAD_PAGE:
1413
		retval = update_flag(CS_SPREAD_PAGE, cs, val);
1414
		cs->mems_generation = cpuset_mems_generation++;
1415 1416
		break;
	case FILE_SPREAD_SLAB:
1417
		retval = update_flag(CS_SPREAD_SLAB, cs, val);
1418
		cs->mems_generation = cpuset_mems_generation++;
1419
		break;
L
Linus Torvalds 已提交
1420 1421
	default:
		retval = -EINVAL;
1422
		break;
L
Linus Torvalds 已提交
1423
	}
1424
	cgroup_unlock();
L
Linus Torvalds 已提交
1425 1426 1427
	return retval;
}

1428 1429 1430 1431 1432 1433
static int cpuset_write_s64(struct cgroup *cgrp, struct cftype *cft, s64 val)
{
	int retval = 0;
	struct cpuset *cs = cgroup_cs(cgrp);
	cpuset_filetype_t type = cft->private;

1434
	if (!cgroup_lock_live_group(cgrp))
1435
		return -ENODEV;
1436

1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448
	switch (type) {
	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
		retval = update_relax_domain_level(cs, val);
		break;
	default:
		retval = -EINVAL;
		break;
	}
	cgroup_unlock();
	return retval;
}

1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474
/*
 * Common handling for a write to a "cpus" or "mems" file.
 */
static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
				const char *buf)
{
	int retval = 0;

	if (!cgroup_lock_live_group(cgrp))
		return -ENODEV;

	switch (cft->private) {
	case FILE_CPULIST:
		retval = update_cpumask(cgroup_cs(cgrp), buf);
		break;
	case FILE_MEMLIST:
		retval = update_nodemask(cgroup_cs(cgrp), buf);
		break;
	default:
		retval = -EINVAL;
		break;
	}
	cgroup_unlock();
	return retval;
}

L
Linus Torvalds 已提交
1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488
/*
 * These ascii lists should be read in a single call, by using a user
 * buffer large enough to hold the entire map.  If read in smaller
 * chunks, there is no guarantee of atomicity.  Since the display format
 * used, list of ranges of sequential numbers, is variable length,
 * and since these maps can change value dynamically, one could read
 * gibberish by doing partial reads while a list was changing.
 * A single large read to a buffer that crosses a page boundary is
 * ok, because the result being copied to user land is not recomputed
 * across a page fault.
 */

static int cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
{
1489
	int ret;
L
Linus Torvalds 已提交
1490

1491
	mutex_lock(&callback_mutex);
1492
	ret = cpulist_scnprintf(page, PAGE_SIZE, &cs->cpus_allowed);
1493
	mutex_unlock(&callback_mutex);
L
Linus Torvalds 已提交
1494

1495
	return ret;
L
Linus Torvalds 已提交
1496 1497 1498 1499 1500 1501
}

static int cpuset_sprintf_memlist(char *page, struct cpuset *cs)
{
	nodemask_t mask;

1502
	mutex_lock(&callback_mutex);
L
Linus Torvalds 已提交
1503
	mask = cs->mems_allowed;
1504
	mutex_unlock(&callback_mutex);
L
Linus Torvalds 已提交
1505 1506 1507 1508

	return nodelist_scnprintf(page, PAGE_SIZE, mask);
}

1509 1510 1511 1512 1513
static ssize_t cpuset_common_file_read(struct cgroup *cont,
				       struct cftype *cft,
				       struct file *file,
				       char __user *buf,
				       size_t nbytes, loff_t *ppos)
L
Linus Torvalds 已提交
1514
{
1515
	struct cpuset *cs = cgroup_cs(cont);
L
Linus Torvalds 已提交
1516 1517 1518 1519 1520
	cpuset_filetype_t type = cft->private;
	char *page;
	ssize_t retval = 0;
	char *s;

1521
	if (!(page = (char *)__get_free_page(GFP_TEMPORARY)))
L
Linus Torvalds 已提交
1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538
		return -ENOMEM;

	s = page;

	switch (type) {
	case FILE_CPULIST:
		s += cpuset_sprintf_cpulist(s, cs);
		break;
	case FILE_MEMLIST:
		s += cpuset_sprintf_memlist(s, cs);
		break;
	default:
		retval = -EINVAL;
		goto out;
	}
	*s++ = '\n';

A
Al Viro 已提交
1539
	retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
L
Linus Torvalds 已提交
1540 1541 1542 1543 1544
out:
	free_page((unsigned long)page);
	return retval;
}

1545 1546 1547 1548 1549 1550 1551 1552 1553
static u64 cpuset_read_u64(struct cgroup *cont, struct cftype *cft)
{
	struct cpuset *cs = cgroup_cs(cont);
	cpuset_filetype_t type = cft->private;
	switch (type) {
	case FILE_CPU_EXCLUSIVE:
		return is_cpu_exclusive(cs);
	case FILE_MEM_EXCLUSIVE:
		return is_mem_exclusive(cs);
1554 1555
	case FILE_MEM_HARDWALL:
		return is_mem_hardwall(cs);
1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570
	case FILE_SCHED_LOAD_BALANCE:
		return is_sched_load_balance(cs);
	case FILE_MEMORY_MIGRATE:
		return is_memory_migrate(cs);
	case FILE_MEMORY_PRESSURE_ENABLED:
		return cpuset_memory_pressure_enabled;
	case FILE_MEMORY_PRESSURE:
		return fmeter_getrate(&cs->fmeter);
	case FILE_SPREAD_PAGE:
		return is_spread_page(cs);
	case FILE_SPREAD_SLAB:
		return is_spread_slab(cs);
	default:
		BUG();
	}
1571 1572 1573

	/* Unreachable but makes gcc happy */
	return 0;
1574
}
L
Linus Torvalds 已提交
1575

1576 1577 1578 1579 1580 1581 1582 1583 1584 1585
static s64 cpuset_read_s64(struct cgroup *cont, struct cftype *cft)
{
	struct cpuset *cs = cgroup_cs(cont);
	cpuset_filetype_t type = cft->private;
	switch (type) {
	case FILE_SCHED_RELAX_DOMAIN_LEVEL:
		return cs->relax_domain_level;
	default:
		BUG();
	}
1586 1587 1588

	/* Unrechable but makes gcc happy */
	return 0;
1589 1590
}

L
Linus Torvalds 已提交
1591 1592 1593 1594 1595

/*
 * for the common functions, 'private' gives the type of file
 */

1596 1597 1598 1599
static struct cftype files[] = {
	{
		.name = "cpus",
		.read = cpuset_common_file_read,
1600 1601
		.write_string = cpuset_write_resmask,
		.max_write_len = (100U + 6 * NR_CPUS),
1602 1603 1604 1605 1606 1607
		.private = FILE_CPULIST,
	},

	{
		.name = "mems",
		.read = cpuset_common_file_read,
1608 1609
		.write_string = cpuset_write_resmask,
		.max_write_len = (100U + 6 * MAX_NUMNODES),
1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626
		.private = FILE_MEMLIST,
	},

	{
		.name = "cpu_exclusive",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_CPU_EXCLUSIVE,
	},

	{
		.name = "mem_exclusive",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEM_EXCLUSIVE,
	},

1627 1628 1629 1630 1631 1632 1633
	{
		.name = "mem_hardwall",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEM_HARDWALL,
	},

1634 1635 1636 1637 1638 1639 1640 1641 1642
	{
		.name = "sched_load_balance",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_SCHED_LOAD_BALANCE,
	},

	{
		.name = "sched_relax_domain_level",
1643 1644
		.read_s64 = cpuset_read_s64,
		.write_s64 = cpuset_write_s64,
1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674
		.private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
	},

	{
		.name = "memory_migrate",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEMORY_MIGRATE,
	},

	{
		.name = "memory_pressure",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_MEMORY_PRESSURE,
	},

	{
		.name = "memory_spread_page",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_SPREAD_PAGE,
	},

	{
		.name = "memory_spread_slab",
		.read_u64 = cpuset_read_u64,
		.write_u64 = cpuset_write_u64,
		.private = FILE_SPREAD_SLAB,
	},
1675 1676
};

1677 1678
static struct cftype cft_memory_pressure_enabled = {
	.name = "memory_pressure_enabled",
1679 1680
	.read_u64 = cpuset_read_u64,
	.write_u64 = cpuset_write_u64,
1681 1682 1683
	.private = FILE_MEMORY_PRESSURE_ENABLED,
};

1684
static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont)
L
Linus Torvalds 已提交
1685 1686 1687
{
	int err;

1688 1689
	err = cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
	if (err)
L
Linus Torvalds 已提交
1690
		return err;
1691
	/* memory_pressure_enabled is in root cpuset only */
1692
	if (!cont->parent)
1693
		err = cgroup_add_file(cont, ss,
1694 1695
				      &cft_memory_pressure_enabled);
	return err;
L
Linus Torvalds 已提交
1696 1697
}

1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711
/*
 * post_clone() is called at the end of cgroup_clone().
 * 'cgroup' was just created automatically as a result of
 * a cgroup_clone(), and the current task is about to
 * be moved into 'cgroup'.
 *
 * Currently we refuse to set up the cgroup - thereby
 * refusing the task to be entered, and as a result refusing
 * the sys_unshare() or clone() which initiated it - if any
 * sibling cpusets have exclusive cpus or mem.
 *
 * If this becomes a problem for some users who wish to
 * allow that scenario, then cpuset_post_clone() could be
 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
1712 1713
 * (and likewise for mems) to the new cgroup. Called with cgroup_mutex
 * held.
1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734
 */
static void cpuset_post_clone(struct cgroup_subsys *ss,
			      struct cgroup *cgroup)
{
	struct cgroup *parent, *child;
	struct cpuset *cs, *parent_cs;

	parent = cgroup->parent;
	list_for_each_entry(child, &parent->children, sibling) {
		cs = cgroup_cs(child);
		if (is_mem_exclusive(cs) || is_cpu_exclusive(cs))
			return;
	}
	cs = cgroup_cs(cgroup);
	parent_cs = cgroup_cs(parent);

	cs->mems_allowed = parent_cs->mems_allowed;
	cs->cpus_allowed = parent_cs->cpus_allowed;
	return;
}

L
Linus Torvalds 已提交
1735 1736
/*
 *	cpuset_create - create a cpuset
1737 1738
 *	ss:	cpuset cgroup subsystem
 *	cont:	control group that the new cpuset will be part of
L
Linus Torvalds 已提交
1739 1740
 */

1741 1742 1743
static struct cgroup_subsys_state *cpuset_create(
	struct cgroup_subsys *ss,
	struct cgroup *cont)
L
Linus Torvalds 已提交
1744 1745
{
	struct cpuset *cs;
1746
	struct cpuset *parent;
L
Linus Torvalds 已提交
1747

1748 1749 1750 1751 1752 1753
	if (!cont->parent) {
		/* This is early initialization for the top cgroup */
		top_cpuset.mems_generation = cpuset_mems_generation++;
		return &top_cpuset.css;
	}
	parent = cgroup_cs(cont->parent);
L
Linus Torvalds 已提交
1754 1755
	cs = kmalloc(sizeof(*cs), GFP_KERNEL);
	if (!cs)
1756
		return ERR_PTR(-ENOMEM);
L
Linus Torvalds 已提交
1757

1758
	cpuset_update_task_memory_state();
L
Linus Torvalds 已提交
1759
	cs->flags = 0;
1760 1761 1762 1763
	if (is_spread_page(parent))
		set_bit(CS_SPREAD_PAGE, &cs->flags);
	if (is_spread_slab(parent))
		set_bit(CS_SPREAD_SLAB, &cs->flags);
P
Paul Jackson 已提交
1764
	set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1765 1766
	cpus_clear(cs->cpus_allowed);
	nodes_clear(cs->mems_allowed);
1767
	cs->mems_generation = cpuset_mems_generation++;
1768
	fmeter_init(&cs->fmeter);
1769
	cs->relax_domain_level = -1;
L
Linus Torvalds 已提交
1770 1771

	cs->parent = parent;
1772
	number_of_cpusets++;
1773
	return &cs->css ;
L
Linus Torvalds 已提交
1774 1775
}

P
Paul Jackson 已提交
1776 1777 1778
/*
 * If the cpuset being removed has its flag 'sched_load_balance'
 * enabled, then simulate turning sched_load_balance off, which
1779
 * will call async_rebuild_sched_domains().
P
Paul Jackson 已提交
1780 1781
 */

1782
static void cpuset_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
L
Linus Torvalds 已提交
1783
{
1784
	struct cpuset *cs = cgroup_cs(cont);
L
Linus Torvalds 已提交
1785

1786
	cpuset_update_task_memory_state();
P
Paul Jackson 已提交
1787 1788

	if (is_sched_load_balance(cs))
1789
		update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
P
Paul Jackson 已提交
1790

1791
	number_of_cpusets--;
1792
	kfree(cs);
L
Linus Torvalds 已提交
1793 1794
}

1795 1796 1797
struct cgroup_subsys cpuset_subsys = {
	.name = "cpuset",
	.create = cpuset_create,
1798
	.destroy = cpuset_destroy,
1799 1800 1801 1802 1803 1804 1805 1806
	.can_attach = cpuset_can_attach,
	.attach = cpuset_attach,
	.populate = cpuset_populate,
	.post_clone = cpuset_post_clone,
	.subsys_id = cpuset_subsys_id,
	.early_init = 1,
};

1807 1808 1809 1810 1811 1812 1813 1814
/*
 * cpuset_init_early - just enough so that the calls to
 * cpuset_update_task_memory_state() in early init code
 * are harmless.
 */

int __init cpuset_init_early(void)
{
1815
	top_cpuset.mems_generation = cpuset_mems_generation++;
1816 1817 1818
	return 0;
}

1819

L
Linus Torvalds 已提交
1820 1821 1822 1823 1824 1825 1826 1827
/**
 * cpuset_init - initialize cpusets at system boot
 *
 * Description: Initialize top_cpuset and the cpuset internal file system,
 **/

int __init cpuset_init(void)
{
1828
	int err = 0;
L
Linus Torvalds 已提交
1829

1830 1831
	cpus_setall(top_cpuset.cpus_allowed);
	nodes_setall(top_cpuset.mems_allowed);
L
Linus Torvalds 已提交
1832

1833
	fmeter_init(&top_cpuset.fmeter);
1834
	top_cpuset.mems_generation = cpuset_mems_generation++;
P
Paul Jackson 已提交
1835
	set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
1836
	top_cpuset.relax_domain_level = -1;
L
Linus Torvalds 已提交
1837 1838 1839

	err = register_filesystem(&cpuset_fs_type);
	if (err < 0)
1840 1841
		return err;

1842 1843 1844
	if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
		BUG();

1845
	number_of_cpusets = 1;
1846
	return 0;
L
Linus Torvalds 已提交
1847 1848
}

1849 1850 1851 1852 1853 1854 1855 1856
/**
 * cpuset_do_move_task - move a given task to another cpuset
 * @tsk: pointer to task_struct the task to move
 * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
 *
 * Called by cgroup_scan_tasks() for each task in a cgroup.
 * Return nonzero to stop the walk through the tasks.
 */
1857 1858
static void cpuset_do_move_task(struct task_struct *tsk,
				struct cgroup_scanner *scan)
1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870
{
	struct cpuset_hotplug_scanner *chsp;

	chsp = container_of(scan, struct cpuset_hotplug_scanner, scan);
	cgroup_attach_task(chsp->to, tsk);
}

/**
 * move_member_tasks_to_cpuset - move tasks from one cpuset to another
 * @from: cpuset in which the tasks currently reside
 * @to: cpuset to which the tasks will be moved
 *
1871 1872
 * Called with cgroup_mutex held
 * callback_mutex must not be held, as cpuset_attach() will take it.
1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886
 *
 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
 * calling callback functions for each.
 */
static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to)
{
	struct cpuset_hotplug_scanner scan;

	scan.scan.cg = from->css.cgroup;
	scan.scan.test_task = NULL; /* select all tasks in cgroup */
	scan.scan.process_task = cpuset_do_move_task;
	scan.scan.heap = NULL;
	scan.to = to->css.cgroup;

L
Lai Jiangshan 已提交
1887
	if (cgroup_scan_tasks(&scan.scan))
1888 1889 1890 1891
		printk(KERN_ERR "move_member_tasks_to_cpuset: "
				"cgroup_scan_tasks failed\n");
}

1892
/*
1893
 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
1894 1895
 * or memory nodes, we need to walk over the cpuset hierarchy,
 * removing that CPU or node from all cpusets.  If this removes the
1896 1897
 * last CPU or node from a cpuset, then move the tasks in the empty
 * cpuset to its next-highest non-empty parent.
1898
 *
1899 1900
 * Called with cgroup_mutex held
 * callback_mutex must not be held, as cpuset_attach() will take it.
1901
 */
1902 1903 1904 1905
static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
{
	struct cpuset *parent;

1906 1907 1908 1909 1910
	/*
	 * The cgroup's css_sets list is in use if there are tasks
	 * in the cpuset; the list is empty if there are none;
	 * the cs->css.refcnt seems always 0.
	 */
1911 1912
	if (list_empty(&cs->css.cgroup->css_sets))
		return;
1913

1914 1915 1916 1917 1918
	/*
	 * Find its next-highest non-empty parent, (top cpuset
	 * has online cpus, so can't be empty).
	 */
	parent = cs->parent;
1919 1920
	while (cpus_empty(parent->cpus_allowed) ||
			nodes_empty(parent->mems_allowed))
1921 1922 1923 1924 1925 1926 1927 1928 1929
		parent = parent->parent;

	move_member_tasks_to_cpuset(cs, parent);
}

/*
 * Walk the specified cpuset subtree and look for empty cpusets.
 * The tasks of such cpuset must be moved to a parent cpuset.
 *
1930
 * Called with cgroup_mutex held.  We take callback_mutex to modify
1931 1932 1933 1934 1935 1936 1937 1938 1939 1940
 * cpus_allowed and mems_allowed.
 *
 * This walk processes the tree from top to bottom, completing one layer
 * before dropping down to the next.  It always processes a node before
 * any of its children.
 *
 * For now, since we lack memory hot unplug, we'll never see a cpuset
 * that has tasks along with an empty 'mems'.  But if we did see such
 * a cpuset, we'd handle it just like we do if its 'cpus' was empty.
 */
1941
static void scan_for_empty_cpusets(struct cpuset *root)
1942
{
1943
	LIST_HEAD(queue);
1944 1945
	struct cpuset *cp;	/* scans cpusets being updated */
	struct cpuset *child;	/* scans child cpusets of cp */
1946
	struct cgroup *cont;
1947
	nodemask_t oldmems;
1948

1949 1950 1951
	list_add_tail((struct list_head *)&root->stack_list, &queue);

	while (!list_empty(&queue)) {
1952
		cp = list_first_entry(&queue, struct cpuset, stack_list);
1953 1954 1955 1956 1957
		list_del(queue.next);
		list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
			child = cgroup_cs(cont);
			list_add_tail(&child->stack_list, &queue);
		}
1958 1959 1960 1961 1962 1963

		/* Continue past cpusets with all cpus, mems online */
		if (cpus_subset(cp->cpus_allowed, cpu_online_map) &&
		    nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))
			continue;

1964 1965
		oldmems = cp->mems_allowed;

1966
		/* Remove offline cpus and mems from this cpuset. */
1967
		mutex_lock(&callback_mutex);
1968 1969 1970
		cpus_and(cp->cpus_allowed, cp->cpus_allowed, cpu_online_map);
		nodes_and(cp->mems_allowed, cp->mems_allowed,
						node_states[N_HIGH_MEMORY]);
1971 1972 1973
		mutex_unlock(&callback_mutex);

		/* Move tasks from the empty cpuset to a parent */
1974
		if (cpus_empty(cp->cpus_allowed) ||
1975
		     nodes_empty(cp->mems_allowed))
1976
			remove_tasks_in_empty_cpuset(cp);
1977
		else {
1978
			update_tasks_cpumask(cp, NULL);
1979 1980
			update_tasks_nodemask(cp, &oldmems);
		}
1981 1982 1983
	}
}

1984 1985 1986 1987 1988 1989
/*
 * The top_cpuset tracks what CPUs and Memory Nodes are online,
 * period.  This is necessary in order to make cpusets transparent
 * (of no affect) on systems that are actively using CPU hotplug
 * but making no active use of cpusets.
 *
1990 1991
 * This routine ensures that top_cpuset.cpus_allowed tracks
 * cpu_online_map on each CPU hotplug (cpuhp) event.
1992 1993 1994
 *
 * Called within get_online_cpus().  Needs to call cgroup_lock()
 * before calling generate_sched_domains().
1995
 */
1996
static int cpuset_track_online_cpus(struct notifier_block *unused_nb,
P
Paul Jackson 已提交
1997
				unsigned long phase, void *unused_cpu)
1998
{
1999 2000 2001 2002
	struct sched_domain_attr *attr;
	cpumask_t *doms;
	int ndoms;

2003 2004 2005 2006 2007 2008
	switch (phase) {
	case CPU_ONLINE:
	case CPU_ONLINE_FROZEN:
	case CPU_DEAD:
	case CPU_DEAD_FROZEN:
		break;
2009

2010
	default:
2011
		return NOTIFY_DONE;
2012
	}
2013

2014 2015 2016 2017 2018 2019 2020 2021 2022
	cgroup_lock();
	top_cpuset.cpus_allowed = cpu_online_map;
	scan_for_empty_cpusets(&top_cpuset);
	ndoms = generate_sched_domains(&doms, &attr);
	cgroup_unlock();

	/* Have scheduler rebuild the domains */
	partition_sched_domains(ndoms, doms, attr);

2023
	return NOTIFY_OK;
2024 2025
}

2026
#ifdef CONFIG_MEMORY_HOTPLUG
2027
/*
2028
 * Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY].
2029 2030
 * Call this routine anytime after node_states[N_HIGH_MEMORY] changes.
 * See also the previous routine cpuset_track_online_cpus().
2031
 */
2032 2033
static int cpuset_track_online_nodes(struct notifier_block *self,
				unsigned long action, void *arg)
2034
{
2035
	cgroup_lock();
2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046
	switch (action) {
	case MEM_ONLINE:
		top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
		break;
	case MEM_OFFLINE:
		top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
		scan_for_empty_cpusets(&top_cpuset);
		break;
	default:
		break;
	}
2047
	cgroup_unlock();
2048
	return NOTIFY_OK;
2049 2050 2051
}
#endif

L
Linus Torvalds 已提交
2052 2053 2054 2055 2056 2057 2058 2059 2060
/**
 * cpuset_init_smp - initialize cpus_allowed
 *
 * Description: Finish top cpuset after cpu, node maps are initialized
 **/

void __init cpuset_init_smp(void)
{
	top_cpuset.cpus_allowed = cpu_online_map;
2061
	top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2062

2063
	hotcpu_notifier(cpuset_track_online_cpus, 0);
2064
	hotplug_memory_notifier(cpuset_track_online_nodes, 10);
L
Linus Torvalds 已提交
2065 2066 2067 2068 2069
}

/**
 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2070
 * @pmask: pointer to cpumask_t variable to receive cpus_allowed set.
L
Linus Torvalds 已提交
2071 2072 2073 2074 2075 2076 2077
 *
 * Description: Returns the cpumask_t cpus_allowed of the cpuset
 * attached to the specified @tsk.  Guaranteed to return some non-empty
 * subset of cpu_online_map, even if this means going outside the
 * tasks cpuset.
 **/

2078
void cpuset_cpus_allowed(struct task_struct *tsk, cpumask_t *pmask)
L
Linus Torvalds 已提交
2079
{
2080
	mutex_lock(&callback_mutex);
2081
	cpuset_cpus_allowed_locked(tsk, pmask);
2082 2083 2084 2085 2086
	mutex_unlock(&callback_mutex);
}

/**
 * cpuset_cpus_allowed_locked - return cpus_allowed mask from a tasks cpuset.
2087
 * Must be called with callback_mutex held.
2088
 **/
2089
void cpuset_cpus_allowed_locked(struct task_struct *tsk, cpumask_t *pmask)
2090
{
2091
	task_lock(tsk);
2092
	guarantee_online_cpus(task_cs(tsk), pmask);
2093
	task_unlock(tsk);
L
Linus Torvalds 已提交
2094 2095 2096 2097
}

void cpuset_init_current_mems_allowed(void)
{
2098
	nodes_setall(current->mems_allowed);
L
Linus Torvalds 已提交
2099 2100
}

2101 2102 2103 2104 2105 2106
/**
 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
 *
 * Description: Returns the nodemask_t mems_allowed of the cpuset
 * attached to the specified @tsk.  Guaranteed to return some non-empty
2107
 * subset of node_states[N_HIGH_MEMORY], even if this means going outside the
2108 2109 2110 2111 2112 2113 2114
 * tasks cpuset.
 **/

nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
{
	nodemask_t mask;

2115
	mutex_lock(&callback_mutex);
2116
	task_lock(tsk);
2117
	guarantee_online_mems(task_cs(tsk), &mask);
2118
	task_unlock(tsk);
2119
	mutex_unlock(&callback_mutex);
2120 2121 2122 2123

	return mask;
}

2124
/**
2125 2126
 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
 * @nodemask: the nodemask to be checked
2127
 *
2128
 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
L
Linus Torvalds 已提交
2129
 */
2130
int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
L
Linus Torvalds 已提交
2131
{
2132
	return nodes_intersects(*nodemask, current->mems_allowed);
L
Linus Torvalds 已提交
2133 2134
}

2135
/*
2136 2137 2138 2139
 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
 * mem_hardwall ancestor to the specified cpuset.  Call holding
 * callback_mutex.  If no ancestor is mem_exclusive or mem_hardwall
 * (an unusual configuration), then returns the root cpuset.
2140
 */
2141
static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs)
2142
{
2143
	while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && cs->parent)
2144 2145 2146 2147
		cs = cs->parent;
	return cs;
}

2148
/**
2149
 * cpuset_zone_allowed_softwall - Can we allocate on zone z's memory node?
2150
 * @z: is this zone on an allowed node?
2151
 * @gfp_mask: memory allocation flags
2152
 *
2153 2154
 * If we're in interrupt, yes, we can always allocate.  If
 * __GFP_THISNODE is set, yes, we can always allocate.  If zone
2155 2156
 * z's node is in our tasks mems_allowed, yes.  If it's not a
 * __GFP_HARDWALL request and this zone's nodes is in the nearest
2157
 * hardwalled cpuset ancestor to this tasks cpuset, yes.
2158 2159
 * If the task has been OOM killed and has access to memory reserves
 * as specified by the TIF_MEMDIE flag, yes.
2160 2161
 * Otherwise, no.
 *
2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175
 * If __GFP_HARDWALL is set, cpuset_zone_allowed_softwall()
 * reduces to cpuset_zone_allowed_hardwall().  Otherwise,
 * cpuset_zone_allowed_softwall() might sleep, and might allow a zone
 * from an enclosing cpuset.
 *
 * cpuset_zone_allowed_hardwall() only handles the simpler case of
 * hardwall cpusets, and never sleeps.
 *
 * The __GFP_THISNODE placement logic is really handled elsewhere,
 * by forcibly using a zonelist starting at a specified node, and by
 * (in get_page_from_freelist()) refusing to consider the zones for
 * any node on the zonelist except the first.  By the time any such
 * calls get to this routine, we should just shut up and say 'yes'.
 *
2176
 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2177 2178
 * and do not allow allocations outside the current tasks cpuset
 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2179
 * GFP_KERNEL allocations are not so marked, so can escape to the
2180
 * nearest enclosing hardwalled ancestor cpuset.
2181
 *
2182 2183 2184 2185 2186 2187 2188
 * Scanning up parent cpusets requires callback_mutex.  The
 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
 * current tasks mems_allowed came up empty on the first pass over
 * the zonelist.  So only GFP_KERNEL allocations, if all nodes in the
 * cpuset are short of memory, might require taking the callback_mutex
 * mutex.
2189
 *
2190
 * The first call here from mm/page_alloc:get_page_from_freelist()
2191 2192 2193
 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
 * so no allocation on a node outside the cpuset is allowed (unless
 * in interrupt, of course).
2194 2195 2196 2197 2198 2199
 *
 * The second pass through get_page_from_freelist() doesn't even call
 * here for GFP_ATOMIC calls.  For those calls, the __alloc_pages()
 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
 * in alloc_flags.  That logic and the checks below have the combined
 * affect that:
2200 2201
 *	in_interrupt - any node ok (current task context irrelevant)
 *	GFP_ATOMIC   - any node ok
2202
 *	TIF_MEMDIE   - any node ok
2203
 *	GFP_KERNEL   - any node in enclosing hardwalled cpuset ok
2204
 *	GFP_USER     - only nodes in current tasks mems allowed ok.
2205 2206
 *
 * Rule:
2207
 *    Don't call cpuset_zone_allowed_softwall if you can't sleep, unless you
2208 2209
 *    pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
 *    the code that might scan up ancestor cpusets and sleep.
2210
 */
2211

2212
int __cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask)
L
Linus Torvalds 已提交
2213
{
2214 2215
	int node;			/* node that zone z is on */
	const struct cpuset *cs;	/* current cpuset ancestors */
2216
	int allowed;			/* is allocation in zone z allowed? */
2217

2218
	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2219
		return 1;
2220
	node = zone_to_nid(z);
2221
	might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
2222 2223
	if (node_isset(node, current->mems_allowed))
		return 1;
2224 2225 2226 2227 2228 2229
	/*
	 * Allow tasks that have access to memory reserves because they have
	 * been OOM killed to get memory anywhere.
	 */
	if (unlikely(test_thread_flag(TIF_MEMDIE)))
		return 1;
2230 2231 2232
	if (gfp_mask & __GFP_HARDWALL)	/* If hardwall request, stop here */
		return 0;

2233 2234 2235
	if (current->flags & PF_EXITING) /* Let dying task have memory */
		return 1;

2236
	/* Not hardwall and node outside mems_allowed: scan up cpusets */
2237
	mutex_lock(&callback_mutex);
2238 2239

	task_lock(current);
2240
	cs = nearest_hardwall_ancestor(task_cs(current));
2241 2242
	task_unlock(current);

2243
	allowed = node_isset(node, cs->mems_allowed);
2244
	mutex_unlock(&callback_mutex);
2245
	return allowed;
L
Linus Torvalds 已提交
2246 2247
}

2248 2249 2250 2251 2252 2253 2254
/*
 * cpuset_zone_allowed_hardwall - Can we allocate on zone z's memory node?
 * @z: is this zone on an allowed node?
 * @gfp_mask: memory allocation flags
 *
 * If we're in interrupt, yes, we can always allocate.
 * If __GFP_THISNODE is set, yes, we can always allocate.  If zone
2255 2256 2257
 * z's node is in our tasks mems_allowed, yes.   If the task has been
 * OOM killed and has access to memory reserves as specified by the
 * TIF_MEMDIE flag, yes.  Otherwise, no.
2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280
 *
 * The __GFP_THISNODE placement logic is really handled elsewhere,
 * by forcibly using a zonelist starting at a specified node, and by
 * (in get_page_from_freelist()) refusing to consider the zones for
 * any node on the zonelist except the first.  By the time any such
 * calls get to this routine, we should just shut up and say 'yes'.
 *
 * Unlike the cpuset_zone_allowed_softwall() variant, above,
 * this variant requires that the zone be in the current tasks
 * mems_allowed or that we're in interrupt.  It does not scan up the
 * cpuset hierarchy for the nearest enclosing mem_exclusive cpuset.
 * It never sleeps.
 */

int __cpuset_zone_allowed_hardwall(struct zone *z, gfp_t gfp_mask)
{
	int node;			/* node that zone z is on */

	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
		return 1;
	node = zone_to_nid(z);
	if (node_isset(node, current->mems_allowed))
		return 1;
D
Daniel Walker 已提交
2281 2282 2283 2284 2285 2286
	/*
	 * Allow tasks that have access to memory reserves because they have
	 * been OOM killed to get memory anywhere.
	 */
	if (unlikely(test_thread_flag(TIF_MEMDIE)))
		return 1;
2287 2288 2289
	return 0;
}

P
Paul Jackson 已提交
2290 2291 2292
/**
 * cpuset_lock - lock out any changes to cpuset structures
 *
2293
 * The out of memory (oom) code needs to mutex_lock cpusets
P
Paul Jackson 已提交
2294
 * from being changed while it scans the tasklist looking for a
2295
 * task in an overlapping cpuset.  Expose callback_mutex via this
P
Paul Jackson 已提交
2296 2297
 * cpuset_lock() routine, so the oom code can lock it, before
 * locking the task list.  The tasklist_lock is a spinlock, so
2298
 * must be taken inside callback_mutex.
P
Paul Jackson 已提交
2299 2300 2301 2302
 */

void cpuset_lock(void)
{
2303
	mutex_lock(&callback_mutex);
P
Paul Jackson 已提交
2304 2305 2306 2307 2308 2309 2310 2311 2312 2313
}

/**
 * cpuset_unlock - release lock on cpuset changes
 *
 * Undo the lock taken in a previous cpuset_lock() call.
 */

void cpuset_unlock(void)
{
2314
	mutex_unlock(&callback_mutex);
P
Paul Jackson 已提交
2315 2316
}

2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354
/**
 * cpuset_mem_spread_node() - On which node to begin search for a page
 *
 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
 * tasks in a cpuset with is_spread_page or is_spread_slab set),
 * and if the memory allocation used cpuset_mem_spread_node()
 * to determine on which node to start looking, as it will for
 * certain page cache or slab cache pages such as used for file
 * system buffers and inode caches, then instead of starting on the
 * local node to look for a free page, rather spread the starting
 * node around the tasks mems_allowed nodes.
 *
 * We don't have to worry about the returned node being offline
 * because "it can't happen", and even if it did, it would be ok.
 *
 * The routines calling guarantee_online_mems() are careful to
 * only set nodes in task->mems_allowed that are online.  So it
 * should not be possible for the following code to return an
 * offline node.  But if it did, that would be ok, as this routine
 * is not returning the node where the allocation must be, only
 * the node where the search should start.  The zonelist passed to
 * __alloc_pages() will include all nodes.  If the slab allocator
 * is passed an offline node, it will fall back to the local node.
 * See kmem_cache_alloc_node().
 */

int cpuset_mem_spread_node(void)
{
	int node;

	node = next_node(current->cpuset_mem_spread_rotor, current->mems_allowed);
	if (node == MAX_NUMNODES)
		node = first_node(current->mems_allowed);
	current->cpuset_mem_spread_rotor = node;
	return node;
}
EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);

2355
/**
2356 2357 2358 2359 2360 2361 2362 2363
 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
 * @tsk1: pointer to task_struct of some task.
 * @tsk2: pointer to task_struct of some other task.
 *
 * Description: Return true if @tsk1's mems_allowed intersects the
 * mems_allowed of @tsk2.  Used by the OOM killer to determine if
 * one of the task's memory usage might impact the memory available
 * to the other.
2364 2365
 **/

2366 2367
int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
				   const struct task_struct *tsk2)
2368
{
2369
	return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2370 2371
}

2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394
/**
 * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
 * @task: pointer to task_struct of some task.
 *
 * Description: Prints @task's name, cpuset name, and cached copy of its
 * mems_allowed to the kernel log.  Must hold task_lock(task) to allow
 * dereferencing task_cs(task).
 */
void cpuset_print_task_mems_allowed(struct task_struct *tsk)
{
	struct dentry *dentry;

	dentry = task_cs(tsk)->css.cgroup->dentry;
	spin_lock(&cpuset_buffer_lock);
	snprintf(cpuset_name, CPUSET_NAME_LEN,
		 dentry ? (const char *)dentry->d_name.name : "/");
	nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
			   tsk->mems_allowed);
	printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
	       tsk->comm, cpuset_name, cpuset_nodelist);
	spin_unlock(&cpuset_buffer_lock);
}

2395 2396 2397 2398 2399 2400
/*
 * Collection of memory_pressure is suppressed unless
 * this flag is enabled by writing "1" to the special
 * cpuset file 'memory_pressure_enabled' in the root cpuset.
 */

2401
int cpuset_memory_pressure_enabled __read_mostly;
2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423

/**
 * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
 *
 * Keep a running average of the rate of synchronous (direct)
 * page reclaim efforts initiated by tasks in each cpuset.
 *
 * This represents the rate at which some task in the cpuset
 * ran low on memory on all nodes it was allowed to use, and
 * had to enter the kernels page reclaim code in an effort to
 * create more free memory by tossing clean pages or swapping
 * or writing dirty pages.
 *
 * Display to user space in the per-cpuset read-only file
 * "memory_pressure".  Value displayed is an integer
 * representing the recent rate of entry into the synchronous
 * (direct) page reclaim by any task attached to the cpuset.
 **/

void __cpuset_memory_pressure_bump(void)
{
	task_lock(current);
2424
	fmeter_markevent(&task_cs(current)->fmeter);
2425 2426 2427
	task_unlock(current);
}

2428
#ifdef CONFIG_PROC_PID_CPUSET
L
Linus Torvalds 已提交
2429 2430 2431 2432
/*
 * proc_cpuset_show()
 *  - Print tasks cpuset path into seq_file.
 *  - Used for /proc/<pid>/cpuset.
2433 2434
 *  - No need to task_lock(tsk) on this tsk->cpuset reference, as it
 *    doesn't really matter if tsk->cpuset changes after we read it,
2435
 *    and we take cgroup_mutex, keeping cpuset_attach() from changing it
2436
 *    anyway.
L
Linus Torvalds 已提交
2437
 */
P
Paul Jackson 已提交
2438
static int proc_cpuset_show(struct seq_file *m, void *unused_v)
L
Linus Torvalds 已提交
2439
{
2440
	struct pid *pid;
L
Linus Torvalds 已提交
2441 2442
	struct task_struct *tsk;
	char *buf;
2443
	struct cgroup_subsys_state *css;
2444
	int retval;
L
Linus Torvalds 已提交
2445

2446
	retval = -ENOMEM;
L
Linus Torvalds 已提交
2447 2448
	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!buf)
2449 2450 2451
		goto out;

	retval = -ESRCH;
2452 2453
	pid = m->private;
	tsk = get_pid_task(pid, PIDTYPE_PID);
2454 2455
	if (!tsk)
		goto out_free;
L
Linus Torvalds 已提交
2456

2457
	retval = -EINVAL;
2458 2459 2460
	cgroup_lock();
	css = task_subsys_state(tsk, cpuset_subsys_id);
	retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
L
Linus Torvalds 已提交
2461
	if (retval < 0)
2462
		goto out_unlock;
L
Linus Torvalds 已提交
2463 2464
	seq_puts(m, buf);
	seq_putc(m, '\n');
2465
out_unlock:
2466
	cgroup_unlock();
2467 2468
	put_task_struct(tsk);
out_free:
L
Linus Torvalds 已提交
2469
	kfree(buf);
2470
out:
L
Linus Torvalds 已提交
2471 2472 2473 2474 2475
	return retval;
}

static int cpuset_open(struct inode *inode, struct file *file)
{
2476 2477
	struct pid *pid = PROC_I(inode)->pid;
	return single_open(file, proc_cpuset_show, pid);
L
Linus Torvalds 已提交
2478 2479
}

2480
const struct file_operations proc_cpuset_operations = {
L
Linus Torvalds 已提交
2481 2482 2483 2484 2485
	.open		= cpuset_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};
2486
#endif /* CONFIG_PROC_PID_CPUSET */
L
Linus Torvalds 已提交
2487 2488

/* Display task cpus_allowed, mems_allowed in /proc/<pid>/status file. */
2489 2490 2491
void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
{
	seq_printf(m, "Cpus_allowed:\t");
2492
	seq_cpumask(m, &task->cpus_allowed);
2493
	seq_printf(m, "\n");
2494
	seq_printf(m, "Cpus_allowed_list:\t");
2495
	seq_cpumask_list(m, &task->cpus_allowed);
2496
	seq_printf(m, "\n");
2497
	seq_printf(m, "Mems_allowed:\t");
2498
	seq_nodemask(m, &task->mems_allowed);
2499
	seq_printf(m, "\n");
2500
	seq_printf(m, "Mems_allowed_list:\t");
2501
	seq_nodemask_list(m, &task->mems_allowed);
2502
	seq_printf(m, "\n");
L
Linus Torvalds 已提交
2503
}